Steam power installation for momentary reserve



June 4, 1935. J. RUTHYS STEAM POWER INSTALLATION FOR MOMENTARY RESERVE Filed April 6, 1951 2 Sheets-Sheet 1 fl INVENTOR?% ATTORNEY June 4, 1935. J. RUTHS 0 STEAM POWER INSTALLATION FOR MOMENTARY RESERVE I Filed April 6, 1951 I 2 Sheets-Sheet 2 ATTOR'NEY Patented June 4, 1935 UNITED STATES STEAM POWER INSTALLATION FOR MOMENTARY RESERVE Johannes Ruths, Djursholm, Sweden, assignor to Ruthsaccumulator Aktiebolag,

Berlin, Germany, a corporation of Sweden Application April 6, 1981,.Serial No. 528,067 In Germany April 5, 1930 4 Claims. (01. 60-94) (Granted under the provisions of sec. 14, act of March 2, 1927; 357 O. 5)

My invention relates to steam power plants, and more particularly to stand by plants which it may be necessary to place in operation suddenly and without warning. In plants of this na- 5 ture, it is common to have a steam accumulator which is kept fully charged so as to be able to supply steam to a turbine on short notice. During the time that the accumulator is supplying the steam, the boiler may be fired and brought up to pressure. Thereupon, the boiler supplies the steam to the turbine as long as it is necessary to keep it in operation.

Many steam turbines are of the type wherein steam is admitted to various pressure stages. Valves operative successively to open the lower pressure stages upon a reduction in turbine speed are provided. Such a turbine is particularly well adapted for use in connection with an accumulator as it makes it possible for a large quantity of low pressure steam, available when the accumulator becomes more or less discharged, to develop the same power as a smaller quantity of high pressure steam. However, when a turbine of this nature is employed in a power plant of the type above referred to, diificulties are experienced in changing over from accumulator steam to boiler steam. These difficulties will be explained in detail hereinafter, and it is one of the objects of my invention to overcome them. 7

Further objects and advantages will be apparent from the following description considered in connection with the accompanying drawings, which form a part of this specification and on which:

Fig. 1 is a chart indicating the mode of operation of the plant according to the present invention;

Fig. 2 shows one embodiment of my invention;

Fig. 3 shows another embodiment of my invention;

Fig. 4 shows a still different embodiment; and

Fig. 5 shows a fourth embodiment of my invention.

Referring more particularly to Fig. 2, reference character t designates a turbine which is mechanically connected to an electric generator. Turbine t is provided with a plurality of inlet valves I, 2 and 3. Valve I admits steam to the highest pressure stage of the turbine, and all the 50 steam admitted through valve I passes through all of the turbine blading. Valve 2 admits steam to an intermediate stage, and this steam passes through approximately two-thirds of the blading. Valve 3 admits steam to the lowest stage, and this steam passes through but approximately one-third of the blading. Obviously, more or less than three stages may be employed. The valves may be controlled by means of a conventional fly-ball governor g which acts to progressively close the valves as the speed of the turbine increases. That is to say, if all the valves are open an increase in' speed will first cause valve :3 to close, then valve 2, and finally valve I will be closed more or less.

Steam is supplied to valves I, 2 and 3 from either an accumulator s or a boiler lc. An over flow valve u, which opens when a predetermined pressure is attained ahead of the valve, is lo cated in the line between theboiler and turbine. Also connected in this line are the reservoir f and the valve V. Located in the conduit I between the accumulator and the turbine is a check valve 1", which allows flow of steam from the accumulator while preventingflow into the accumulator.

The generator which is connected to turbine t is electrically connected to a net work which is normally supplied with current by a main power plant normally able to carry the entire electric load on the net work. Under such conditions, the generator floats on the line and operates as a motor driving the rotor of turbine t. The governor g is designed to maintain all of the valves I, 2 and 3 closed under these conditions. In the event of any failure in the supply of current to the net work, the generator connected to turbine t, which has been operating as a motor, starts to slow down. The same thing happens if the electric load increases, as this increase causes the turbo-generator sets of the main power plant to slow down, whereupon the frequency of the current supplied thereby to the net work is reduced and the generator connected to turbine t, which has been running as a motor, slows down. Thereupon the governor opens valve I and admits steam to the turbine from the accumulator s, which is maintained charged at, for instance, I 3 atmospheres pressure. Assume that this takes place at the time indicated on the chart shown in Fig. 1. If the generator has a capacity of 10,000 kw. the turbine may require approximate- 1y 70,000 kg./hr. of saturated steam supplied by the accumulator at 13 atmospheres pressure to develop this power. At this time, steps are taken to bring the boiler 7c up to pressure. I

During the operation of the turbine on accumulator steam, the accumulator becomes discharged and the pressure of the steam therein drops, as indicated by the line P5 in Fig. 1. As the pressure oi the accumulator steam drops, more of it is required to develop the 10,000 kw.

This increased quantity of steam is not able to pass through valve I and consequently the turbine slows down slightly, whereupon the governor opens valve 2. Accumulator steam is now fed to the turbine through both of these valves. The opening of valve 2 takes place at the time b on the chart. accumulator pressure still more and finally valve 3 is opened, whereupon steam is admitted to the turbine through all three of the valves. Approximately 110,000 kg./hr. of this low pressure steam is required to develop 10,000 kw.

At this time, indicated by d on the chart, the boiler has been brought up tov pressure. This boiler has a capacity of approximately 50,000

kg./hr. of steam at 13 atmospheres pressure and 350 C. Steam at this pressure and temperature has approximately 280" of supe'rheat, 50,000 kg./hr. of steam superheat to this degree is able to carry the full load on turbine if all the available energy is extracted from the steam. Con sequently, a boiler of this capacity is large enough to operate the turbine. At the time d, however, 110,000 kg./h. are required. At time d the supply of steam begins from the boiler. At a boiler pressure at 13 atmospheres and a steam temperature of 350, the consumption of live steam amounts to 50,000 kg./h. for 10,000 kw. This is shown by line Dk in Fig. 2. At time d the overflow valve u will begin to open, and live steam together with steam from the accumulator will enter the lowest turbine stage 3, which is open at this time. A quantity of steam amounting to 110,000 kg./h. being required for this turbine stage, whereas the boiler without stress can only supply 50,000 kg./h., it follows that 110,000 minus- 50,000=60,000 kg./h. steam will have to be taken continuously from the accumulator, so that the check valve 1 does not close and the accumulator is still further discharged. The high pressure boiler steam is being throttled down to the pressure of stage 3, which causes an increase of entropy and a loss of a large portion of heat which has been applied by firing to the boiler. Besides,

' the accumulator will be discharged to an unpermissible degree of low pressure.

In order to overcome this difficulty the reservoir ,f and the valve V are placed in the steam line from the boiler. The valve V is maintained closed until the boiler is up to full pressure and hence the reservoir I will be full of steam at this pressure. If the valve V is now suddenly opened the boiler and the reservoir are able to supply steam at the rate of more than 110,000 kg./hr. for the few seconds that is necessary to increase the speed of the turbine sufficiently to close valves 3 and 2. Thereafter, the normal boiler supply of 50,000 kg./hr. is suificient to maintain the turbine at the normal speed and to maintain only valve I open. Check valve 2 prevents the flow of the high pressure boiler steam into the accumulator s.

According to Fig. 3, separate conduits are provided for conveying steam from the accumulator to the highest and the two lower pressure stages, respectively, and the boiler is connected to the conduit leading to the highest pressure stage. A check valve is placed in this conduit between its connections to the branch pipe leading to the lower stages and the boiler supply pipe. In case the over-flow valve opens, owing to the check valve 1 only the first pressure stage can be supplied with steam from the boiler. The pressure prevailing in the first stage is such that the amount of steam supplied from the boiler is able Further operation reduces the to develop the required kw. output. Owing to the fact that at this time the lower pressure stages of the turbine are open and fed by steam from the accumulator, an increase of speed is attained and in consequence the speed regulator g shuts off the lower stages and hence the supply of steam from the accumulator, the further work being done only by steam from the boiler.

Fig. lillustrates the invention in case the turbine is regulated by sets of nozzles. At the beginning-of a disturbance in the electrical system, the speed regulator'first opens the supply pipe 1 leading to-the of nozzles, allowing the steam from the accumulator to enter the pipe I by Way of the check valves 1'3, T2, and m. At progressing drop of the pressure or" the accumulator, the speed regulator opens the supply pipe 2 leading to the second, and later also opens the supply pipe 3 leading to the further sets of nozzles.

Valves controlled by pressure are placed in the steam supply piping of the boiler leading to each set of the nozzles. Said valves can be opened in'proper order consecutively, corresponding to the boiler pressure. The steam-first entering the piping i causes the check valve 1'1 to close. As the steam from the boiler has a larger drop of heat than the storage steam finally supplied to the first set of nozzles, the number of revolutions of the engine will increase and the steam regulator will begin to close the supply to the third set of nozzles. Owing to a further increase of the boiler pressure the regulator (1 opens also the supply of the second set of nozzles. In consequence the speed regulator further closes the sup-ply or" steam from the accumulator. This continued until finally the engine is driven by boiler steam only.

Fig. 5 designates another solution of the problem. The instant the boiler starts the supply of steam, an additional electrical output is generated by means of an additional engine or additional stage t2 outside of the accumulator operated steam turbine. The output supplied by this additional turbine or stage causes the speed regulator g to close the lower stages of the low pressure turbine 73, with the result that the boiler steam received from the additional turbine or stage 252 can only supply the first stage of the low pressure turbine. The steam accumulator is again shut 01f by the check valve 1'. It is understood that the engines ti and 132 can be joined by means of the same shaft.

What I claim is:-

. 1. In a power plant having a boiler, an accumulator, a turbine, means to conduct steam to the turbine from the boiler and from the accumulator, said turbine having a plurality of steam inlets at points of different pressure, valves for controlling supply of steam to said inlets, and means responsive to the speed of the turbine for successively opening and closing the valves, the last mentioned means operating on decrease of speed to open the valves in the order of decreasing pressure, the combination therewith of means operable when the boiler starts to supply steam to the turbine to cause this steam to produce an increase in turbine speed for closing one or more of the valves in the low pressure inlets of said turbine.

2. In a power plant having a boiler, an accumulator, a turbine, means to conduct steam to the turbine from the boiler and from the accumulator, said turbine having a plurality of steam inlets at points of difierent pressure, valves for controlling supply of steam to said inlets, and means responsive to the speed of the turbine for successively opening and closing the valves, the last mentioned means operating on decrease of speed to open the valves in the order of decreasing pressure, the combination therewith of means operable when the boiler starts to supply steam to the turbine to cause this steam to produce an increase in turbine speed for closing one or more of the valves in the low pressure inlets of said turbine, the last mentioned means including a steam reservoir connected to the path of flow of steam from the boiler to the turbine and a valve between the reservoir and the turbine.

3. In a power plant having a boiler, an accumulator, a turbine, a conduit for flow of steam from the accumulator to the turbine, a check valve in said conduit, a conduit connected to the boiler and to the first mentioned conduit between the check valve and the turbine, said turbine having a plurality of steam inlets at points of difierent pressure, valves for controlling supply of steam to said inlets and means responsive to the speed of the turbine for successively opening and. closing the valves, the last mentioned 'means operating on decrease of speed to open the valves in the order of decreasing pressure, the combination therewith of means operable when the boiler starts to supply steam to the turbine to cause this steam to produce an increase in turbine speed for closing one or more of the valves in the low pressure inlets of said turbine.

4. In a power plant, a boiler, an accumulator, a turbine, said turbine having a plurality of steam inlets at points of different pressure, valves for controlling supply of steam to said inlets, means responsive to the speed of the turbine for successively opening and closing the valves, said means operating on decrease of speed to open the valves in the order of decreasing pressure, means for supplying steam from said accumulator to all of said inlets, and means for supplying steam from said boiler to the highest pres-- sure inlet only, whereby, when the boiler starts to supply steam, this steam causes an increase in turbine speed for closing one or more of the valves in the low pressure inlets.

J OHANNES RUTHS. 

